---Someone is knocking at the door. Who may it be?---It ______ be Tom. He is still in the school.
Yesterday Mr. Wang told us the earth always ____ around the sun.
—Do you know when ____? I miss him very much.—Don’t worry. I will tell you as soon as ____.
—Would you like to stay ____ days in Beijing?—No, thanks. I’m afraid I’ll be back tomorrow.
—Mr. Wang, I have trouble ____ the text.—Remember ____ it three times at least.
One of my teachers ____ an Englishman.